Term first used by Gertrude Schmeidler to describe the relationship between acceptance of the possibility of extrasensory perception occurring under the given experimental conditions, and the level of scoring actually achieved on that ESP test: subjects who do not reject the possibility (“sheep”) tend to score above chance, those rejecting the possibility (“goats”) at or below chance; the terms “sheep” and “goat” are nowadays often used in a more extended sense, and “sheep-goat effect” may thus refer to any significant scoring difference between these two groups as defined by the experimenter.